Restart Hyper-V Host

Summary

This script safely restarts a standalone Hyper-V host from within CW Automate, while preserving the state of every virtual machine (VM) running on it.

When triggered, the script performs the following steps on the target host:

1. Downloads and verifies the restart script from our secure content repository. Every download is checked against our code-signing certificate before it runs, so only trusted, unmodified code is executed on your systems.

2. Prepares the VMs for reboot. All running VMs are safely suspended, meaning their current state is saved to disk. This is similar to hibernating a laptop: the VMs pause exactly where they are and pick up right where they left off after the reboot.

3. Restarts the host. Once every VM has been suspended and confirmed as saved, the host reboots.

4. Restores everything automatically. After the host comes back online, a built-in post-reboot task waits for the Hyper-V service to start, then resumes each VM from its saved state. The task then removes itself, leaving no leftover artifacts.

Built-in safety: If any VM fails to suspend before the reboot, the script automatically resumes all VMs that were already suspended and cancels the reboot. The host is never left in a partially suspended state.

Monitoring: CW Automate monitors the post-reboot restore process and reports one of three statuses:

• Success -- All VMs have been resumed on the host.
• Continue -- The restore is still in progress; no action is needed.
• Failure -- The restore did not complete; manual investigation is required. Details are included in the script output.

Note: This script is designed for standalone Hyper-V hosts that are not part of a failover cluster. For clustered environments, use the Restart Cluster Node script instead, which live-migrates clustered VMs to a neighbor node so they remain online during the reboot.

Note: Because VMs are suspended rather than live-migrated, there is a brief period during the reboot window when the VMs are paused. Workloads inside the VMs will experience this as a short interruption, similar to a host going into and coming out of hibernation.

Dependencies

• Restart-HyperVHost

Sample Run

Global Variables

Name	Value	Accepted Values	Description
Debug	False	False, True	When True, enables informational logging; when False (default), informational logs are suppressed to avoid adding entries to the h_scripts table. Set to True to assist with troubleshooting.
ScriptEngineEnableLogger	False	False, True	When True, enables final (success/failure) logging; when False (default), these logs are suppressed to avoid adding entries to the h_scripts table. Set to True to assist with troubleshooting.
TimeoutMinutes	30	Any positive integer	The maximum number of minutes CW Automate will wait for the post-reboot restore process to complete before reporting a failure. If the VMs have not been fully resumed within this window, the monitor flags the host for manual investigation. Increase this value for hosts with a large number of VMs or slower storage, where the resume process may take longer.

Output

• Script Logs

Changelog

2026-07-29

• Initial version of the document.